Printed circuit connector spring contact device



Dec. 23, 1969 H 35 VUYST ET AL 3,486,163

PRINTED CIRCUIT CONNECTOR SPRING CONTACT DEVICE Filed Jan. 25, 1968 2Sheets-Sheet 2 H.R.N. DsVuvrr J. J'- Dearmantk United States Patent3,486,163 PRINTED CIRCUIT CONNECTOR SPRING CONTACT DEVICE Hugo RichardNatalis De Vuyst, Lange Rekstraat 15, St. Niklaas Waas, East Flanders,Belgium, and Joseph Julien Dereymaeker, Kouterdreef 37, Mecheleu,Antwerp, Belgium Filed Jan. 25, 1968, Ser. No. 700,450 Claims priority,application Belgium, Jan. 31, 1967, 693,430 Int. Cl. H011 21/28 US. Cl.3364 2 Claims ABSTRACT OF THE DISCLOSURE A fork-shaped contact elementto be used in electrical connectors of the type which engage the conductr-bearing edge of printed circuit boards. The contact includes aresilient fork-shaped forward end which straddles the edge of a circuitboard, and an integral rear tail portion which serves as an anchor andas a terminal post for securing external conductors to the contact. Anintegral weakened portion between the tail and the forward end acts as aresilient hinge to permit alignment motion of the forward end relativeto a connector housing when the tail portion has been anchored to thehousing.

This invention relates, in general, to electrical connectors of theedge-engaging type for printed circuit boards. More specifically, itrelates to fork-shaped contact elements for use in such electricalconnectors, wherein provision is made for accommodating variations inalignment of parts without affecting the contact pressure between matingconductive surfaces.

The prior art contains examples of connectors for printed circuit boardsin which individual contact elements have fork-shaped forward ends forstraddling inserted circuit boards, and rearward tail portions foranchoring the contacts within a connector housing. The two arms of theforked ends generally are of resilient structure, so as to provide aspringy pincer grip on opposite sides of an inserted board.

In the prior art devices of this type, it has been customary to attachthe fork arms rigidly to the extending tail. Because of this, the forceof the pincer grip may be reduced substantially by even a slightmisalignment of the inserted circuit board relative to the position ofthe tail anchor portion. Such misalignment may occur easily as a resultof variations in dimensional tolerances in the circuit boards and in thepositioning of contact elements within a connector housing.

Some of the prior art contact elements have had the additionaldisadvantage of two-part construction. In these, a separate forkedspring member is employed, to obtain the desired resilience, incombination with a conductor part or parts which have optimum conductiveproperties. Such two-part construction involves added expense inmaterials and in assembly costs, and does not succeed in eliminating anyof the misalignment problems mentioned above.

Accordingly, it is an object of this invention to provide a resilientcontact element of forked-arm construction, for printed circuit boards,in which gripping force between the fork arms is substantiallyindependent of misalignment between the board and the contact.

A further object of this invention is the provision of a contact elementof the type described which can be fabricated easily and inexpensivelyfrom a unitary piece of blank stock.

A feature of this invention is the provision of an integral weakenedportion between the forward forked end of the contact and the rearwardanchor portion so that the fork may change position as a unit relativeto the anchor.

These and other and further objects, features and advantages of thisinvention will be more particularly pointed out and distinctly claimedin the following specification and claims, considered in conjunctionwith the accompanying drawings, in which:

FIGURES 1 and 2 are transverse sectional views through a connector forprinted circuit boards, constructed in accordance with this invention,and showing insertion of a circuit board in aligned and misalignedpositions, respectively;

FIGURE 3 is a perspective view of a blank from which a contact elementmay be formed in accordance with this invention;

FIGURE 4 is a section view taken along line IVIV of FIGURE 3;

FIGURE 5 is a section view taken long line V--V of FIGURE 3;

FIGURES 6 through 9 are perspective representations of progressivestages in the formation of a contact element from the blank illustratedin FIGURE 3.

Referring to the drawings more particularly, it may be seen that FIGURE1 illustrates a contact element 2 disposed within a connector housing 1of insulating material. The contact element comprises: a forked forwardend formed of fork arms 4 and connecting base portion 10, a rearwardtail or terminal post 3, and an integral connecting portion 8 ofweakened structure formed between post 3 and base 10. The forward ends 5of fork arms 4 are bent so as to form a pair of opposed contact surfaces6. As illustrated in FIGURE 1 contact surfaces 6 will be urged intoengagement with opposite sides of a printed circuit board 7 insertedbetween them. The resilience of arms 4 and base 10 provides the forcefor engagement of surfaces 6 with a board 7.

It should be noted that arms 4 and base 10 form a unit in which thepincer gripping force exerted by the arms is substantially independentof any external structure. This unit, formed of arms 4 and base 10, isintegrally coupled to terminal anchor post 3 by weakened connectingportion 8. The weakened portion acts in the manner of a flexible hingeto permit the forked forward end to be deflected as a unit relative to afixed position of post 3. The advantageous result of this flexure may beseen readily from comparison of FIGURES 1 and 2 of the drawings. InFIGURE 1, circuit board 7 has been inserted between fork arms 4 alongthe center line which is defined by the undefiected position of contact2 within housing 1. In FIGURE 2 circuit board 7 has been insertedbetween arms 4 along a plane which is displaced from the at rest centerline described above. As a result of inserting circuit board 7 in thismanner, fork arms 4 and base 10 have been deflected as a unit abouthinge 8 from their at rest position, so as to grip the circuit boardwith substantially undiminished force in the new position. The flexureof weakened portion 8 which allows accommodation of the misalignment, isshown clearly. I

A contact element capable of performing in the manher which has beendescribed may be constructed readily from a blank shaped as shown inFIGURE 3. The weakened hinge portion 8 may be formed by means of astamping or swaging operation to change the cross-sectionalconfiguration of that portion of terminal post 3 from the shape shown inFIGURE 5 to that shown in FIGURE 4. The reduced thickness of portion 8,produced by this operation, readily permits flexure of the contactelement at this point as has been described.

To achieve the forked-shape shown in FIGURES 1 and 2, the blank ofFIGURE 3 may be bent first at the ends of arms 4 and 4 as shown inFIGURE 6. Then, arm 4 may be twisted 90 degrees about its axis over thelength 1 relative to hooked portion 12 as shown in FIGURE 7. This stepis necessary so as to bring arm 4 into proper position for ultimateopposition to arm 4 It should be noted that the blank shown in FIGURE 3may be formed preferably by having leg 4 initially disposedsubstantially perpendicularly to leg 4 and then bending the leg first asshown at reference point 11 and then as shown at reference point 12 toachieve the hooked step 13. This procedure enhances the resilience ofthe fork which is eventually defined by these two arms.

Following the step shown in FIGURE 7, the extention portion 12 on leg 4may be bent up out of the plane of the blank, as shown at 11 in FIGURE8, and connecting portion may be further bent at right angles to theinitial plane of the blank so as to bring arms 4 and 4 into the opposedposition illustrated at FIGURE 9.

The foregoing steps and operations will result in the formation of acontact element 2 in which the forward arms 4 will be able to floatfreely, in effect, about hinge portion 8 relative to the interior cavityof a housing 1 which has been firmly anchored to the tail post portion 3of the contact element.

The invention has thus been described but it is desired to be understoodthat it is not confined to the particular forms or usages shown anddescribed, the same being merely illustrative, and that the inventionmay be carried out in other ways Without departing from the spirit ofthe invention; therefore, the right is broadly asserted to employ allequivalent instrumentalities coming Within the scope of the invention,and by means of which objects of this invention are attained and newresults accomplished, as it is obvious that the particular embodimentsherein shown and described are only some of the many that can beemployed to obtain these objects and accomplish these results.

We claim:

1. An electrical contact device, for an electrical connector for printedcircuit boards and the like, integrally formed of a unitary piece ofblank stock having a given surface and comprising:

a forward forked end having a pair of opposed contact arms and a baseelement resiliently coupling said arms together for engaging a flatcircuit conductor therebetween;

a rearward tail portion capable of being securely anchored to aconnector housing;

a stiflly flexible hinge portion coupling said tail portion to saidforked end;

wherein one of said pair of opposed contact arms is initially disposedsubstantially perpendicularly to the other of said arms in a commonplane, and the said one of said arms is rotated about its ownlongitudinal axis and is bent out of the plane of said fiat blank so asto bring the given surface of said blank stock on said one arm intosubstantially opposed relationship with the same given surface of saidblank stock on the other of said arms.

2. An electrical contact device in accordance with claim 1 wherein saidhinge'portion comprises a non-elastically deformed section of said blankstock.

References Cited UNITED STATES PATENTS 2,755,450 7/1956 Chapman 339-642,911,609 11/1959 Burtt et al 339-176 X 3,172,718 3/1965 Lalonde 339-276K 3,192,498 6/1965 Ruehlemann 339--33 3,231,848 1/1966 Ruehlemann 339276X RICHARD E. MOORE, Primary Examiner US. Cl. X.R. 339 217, 25s, 27s

